Techniques for restoring structure and function to damaged tissue are used routinely in the field of plastic surgery, including reconstructive and cosmetic surgery. Tissue transplantation is one way of restoring structure and function by replacing or rebuilding the damaged tissue. The transfer of biological material from one individual to another can raise significant risks. One such risk is tissue rejection, which can occur even in cases where there is a good histocompatibility match. The risk of tissue rejection can be reduced by processing tissues so that they become essentially free of cell components (e.g., cellular membranes, nucleic acids, lipids, and cytoplasmic components) that cause immunogenic responses. Such tissues are sometimes referred to as decellularized, cell-free, or acellular matrices. It is also desirable to retain the growth factors that are required to promote cellular ingrowth into the acellular matrix, eventually replacing the acellular matrix with the patient's native tissue.
In particular, injectable soft tissue fillers have expanded the non-surgical options available for volume replacement, facial defect filling and rejuvenation in the aging face. Injectable soft tissue fillers are widely used for both superficial and deep aesthetic applications, including lip augmentation or rejuvenation of the aging lip to restore shape and contour, fine line filling to reduce the appearance of wrinkles around the eyes or mouth, improvement of nasolabial folds, correction of eyelid deformities, volume filling for the cheek and jawline, and for deep wrinkle or scar filling.
There are many soft tissue fillers that are commercially available for these applications, and in general, fall within the following categories: autologous implant materials, collagens, hyaluronic acid (HA), and biosynthetic polymers. Durability of these materials varies from several weeks to years, or is considered permanent.